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    <title>ActiveRecord::ConnectionAdapters::DatabaseLimits</title>
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            <span>Ruby on Rails v4.0.0</span><br />
        
        <h1>
            <span class="type">Module</span> 
            ActiveRecord::ConnectionAdapters::DatabaseLimits 
            
        </h1>
        <ul class="files">
            
            <li><a href="../../../files/activerecord/lib/active_record/connection_adapters/abstract/database_limits_rb.html">activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb</a></li>
            
        </ul>
    </div>
    <div id="bodyContent">
        <div id="content">
  


  


  
  


  


  
    <!-- Method ref -->
    <div class="sectiontitle">Methods</div>
    <dl class="methods">
      
        <dt>A</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-allowed_index_name_length">allowed_index_name_length</a>
              </li>
            
          </ul>
        </dd>
      
        <dt>C</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-column_name_length">column_name_length</a>,
              </li>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-columns_per_multicolumn_index">columns_per_multicolumn_index</a>,
              </li>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-columns_per_table">columns_per_table</a>
              </li>
            
          </ul>
        </dd>
      
        <dt>I</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-in_clause_length">in_clause_length</a>,
              </li>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-index_name_length">index_name_length</a>,
              </li>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-indexes_per_table">indexes_per_table</a>
              </li>
            
          </ul>
        </dd>
      
        <dt>J</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-joins_per_query">joins_per_query</a>
              </li>
            
          </ul>
        </dd>
      
        <dt>S</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-sql_query_length">sql_query_length</a>
              </li>
            
          </ul>
        </dd>
      
        <dt>T</dt>
        <dd>
          <ul>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-table_alias_length">table_alias_length</a>,
              </li>
            
              
              <li>
                <a href="DatabaseLimits.html#method-i-table_name_length">table_name_length</a>
              </li>
            
          </ul>
        </dd>
      
    </dl>
  

  



  

    

    

    


    


    <!-- Methods -->
        
      <div class="sectiontitle">Instance Public methods</div>
      
        <div class="method">
          <div class="title method-title" id="method-i-allowed_index_name_length">
            
              <b>allowed_index_name_length</b>()
            
            <a href="DatabaseLimits.html#method-i-allowed_index_name_length" name="method-i-allowed_index_name_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum allowed length for an index name. This limit is
enforced by rails and Is less than or equal to
<code>index_name_length</code>. The gap between
<code>index_name_length</code> is to allow internal rails operations to use
prefixes in temporary operations.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-allowed_index_name_length_source')" id="l_method-i-allowed_index_name_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L25" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-allowed_index_name_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 25</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">allowed_index_name_length</span>
  <span class="ruby-identifier">index_name_length</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-column_name_length">
            
              <b>column_name_length</b>()
            
            <a href="DatabaseLimits.html#method-i-column_name_length" name="method-i-column_name_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum length of a column name.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-column_name_length_source')" id="l_method-i-column_name_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L11" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-column_name_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 11</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">column_name_length</span>
  <span class="ruby-number">64</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-columns_per_multicolumn_index">
            
              <b>columns_per_multicolumn_index</b>()
            
            <a href="DatabaseLimits.html#method-i-columns_per_multicolumn_index" name="method-i-columns_per_multicolumn_index" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum number of columns in a multicolumn index.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-columns_per_multicolumn_index_source')" id="l_method-i-columns_per_multicolumn_index_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L45" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-columns_per_multicolumn_index_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 45</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">columns_per_multicolumn_index</span>
  <span class="ruby-number">16</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-columns_per_table">
            
              <b>columns_per_table</b>()
            
            <a href="DatabaseLimits.html#method-i-columns_per_table" name="method-i-columns_per_table" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum number of columns per table.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-columns_per_table_source')" id="l_method-i-columns_per_table_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L35" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-columns_per_table_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 35</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">columns_per_table</span>
  <span class="ruby-number">1024</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-in_clause_length">
            
              <b>in_clause_length</b>()
            
            <a href="DatabaseLimits.html#method-i-in_clause_length" name="method-i-in_clause_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum number of elements in an IN (x,y,z) clause. nil means
no limit.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-in_clause_length_source')" id="l_method-i-in_clause_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L51" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-in_clause_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 51</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">in_clause_length</span>
  <span class="ruby-keyword">nil</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-index_name_length">
            
              <b>index_name_length</b>()
            
            <a href="DatabaseLimits.html#method-i-index_name_length" name="method-i-index_name_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum length of an index name.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-index_name_length_source')" id="l_method-i-index_name_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L30" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-index_name_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 30</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">index_name_length</span>
  <span class="ruby-number">64</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-indexes_per_table">
            
              <b>indexes_per_table</b>()
            
            <a href="DatabaseLimits.html#method-i-indexes_per_table" name="method-i-indexes_per_table" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum number of indexes per table.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-indexes_per_table_source')" id="l_method-i-indexes_per_table_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L40" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-indexes_per_table_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 40</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">indexes_per_table</span>
  <span class="ruby-number">16</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-joins_per_query">
            
              <b>joins_per_query</b>()
            
            <a href="DatabaseLimits.html#method-i-joins_per_query" name="method-i-joins_per_query" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns maximum number of joins in a single query.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-joins_per_query_source')" id="l_method-i-joins_per_query_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L61" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-joins_per_query_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 61</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">joins_per_query</span>
  <span class="ruby-number">256</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-sql_query_length">
            
              <b>sql_query_length</b>()
            
            <a href="DatabaseLimits.html#method-i-sql_query_length" name="method-i-sql_query_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum length of an SQL query.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-sql_query_length_source')" id="l_method-i-sql_query_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L56" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-sql_query_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 56</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">sql_query_length</span>
  <span class="ruby-number">1048575</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-table_alias_length">
            
              <b>table_alias_length</b>()
            
            <a href="DatabaseLimits.html#method-i-table_alias_length" name="method-i-table_alias_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum length of a table alias.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-table_alias_length_source')" id="l_method-i-table_alias_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L6" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-table_alias_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 6</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">table_alias_length</span>
  <span class="ruby-number">255</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
        
        <div class="method">
          <div class="title method-title" id="method-i-table_name_length">
            
              <b>table_name_length</b>()
            
            <a href="DatabaseLimits.html#method-i-table_name_length" name="method-i-table_name_length" class="permalink">Link</a>
          </div>
          
          
            <div class="description">
              <p>Returns the maximum length of a table name.</p>
            </div>
          
          
          
          
          
            
            <div class="sourcecode">
              
              <p class="source-link">
                Source: 
                <a href="javascript:toggleSource('method-i-table_name_length_source')" id="l_method-i-table_name_length_source">show</a>
                
                  | <a href="https://github.com/rails/rails/blob/55686dd1be37d6eb57dc086e4bc72922f49b2e17/activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb#L16" target="_blank" class="github_url">on GitHub</a>
                
              </p>
              <div id="method-i-table_name_length_source" class="dyn-source">
                <pre><span class="ruby-comment"># File activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb, line 16</span>
<span class="ruby-keyword">def</span> <span class="ruby-keyword ruby-title">table_name_length</span>
  <span class="ruby-number">64</span>
<span class="ruby-keyword">end</span></pre>
              </div>
            </div>
            
          </div>
                    </div>

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